Computed Tomography in its transmission (CT), emission (PET, SPECT), and soon Nuclear Magnetic Resonance (NMR) modalities, represents the main research area of the Neuroradiology and Computed Tomography Section. CT: Ongoing clinical - animal/experimental research projects in transmission CT include studies of degenerative, demyelinating and atrophic processes of the brain, hydrorocephalus, brain edema, postradiation cerebral necrosis, surgically correctable lesions in young patients affected by chronic epilepsy, diseases and abnormal (e.g. tumoral) cerebral tissue, and an experimental glioma model in primates. Physics projects: Improved dual-energy CT scanning using both a split-detector and a dual kVp method; analysis of aliasing effects and development of methods for their elimination; phantom studies for the evaluation of artifacts and calibration of CT machines; feasibility tests for a new type of CT device which used protons instead of x-rays. NMR: Our NMR imaging research is developing along three main lines: l) we are taking advantage of the exquisite capability of NMR to display fine anatomical detail to advance our diagnostic yield in a number of neurological lesions; 2) we are trying to learn more about the NMR signal of various tissues, starting with the signal from extravasated blood (various types of CNS hemorrhages); and 3) we are comparing out clinical NMR imaging results with those of CT and particularly PET in a variety of abnormal conditions starting with CNS tumors.